A sliding surface of the rolling bearing and that of the cage are supplied with lubricating oil or lubricating grease to decrease rolling friction or sliding friction. The sliding surface is subjected to surface treatment to improve the sliding property thereof. As a known surface treatment method, a fluorine-based resin film is formed on the sliding surface. For example, as a known method, a polytetrafluoroethylene film (hereinafter referred to as PTFE) formed on a sliding portion of a sliding member is irradiated with radiation rays having a dose of 50 to 250 kGy to enhance the wear resistance and adhesiveness of the sliding member to the base material (patent document 1).
In a known method of producing a modified fluororesin coating material, a film of fluororesin is formed on the surface of a base material, excellent in its heat resistance, which is composed of a material selected from among polyimide resin; a metal material such as copper, aluminum, alloys thereof; ceramics; and glass and thereafter the fluororesin film is irradiated with ionizing radiation at a temperature not less than the melting point of the fluororesin (patent document 2).
A sliding member, comprising fluororesin, which is used for a non-lubricated bearing, dynamic seal, and the like is known. The fluororesin is heated up to a temperature not less than its crystalline melting point and thereafter irradiated with ionizing radiation within a range of an irradiation dose of 1 kGy to 10 MGy under the absence of oxygen (patent document 3).
A rolling bearing, particularly a needle roller bearing having a cage is used in engines of cars, motor bicycles, and the like. To prevent the surface of the cage from being subjected to seizure, the surface thereof is silver-plated. The needle roller bearing having the cage is composed of a pressed metal cage which retains needle rollers at regular intervals. The entire surface of the cage is silver-plated (patent document 4).